Draconis
ElCeejo

Adds advanced Dragons and powerful equipment.

Multiple Biome Generator
chaosomnium

230 Pseudorandomly Generated Biomes, Trees, Fruits, Ores, Tools, and Liquids

Alien Material
debiankaios

Adds new blocks, items, and tools from aliens. A new time begins.

Kitty/Kitto Ores
nemokitty9

Nemokitty9's own ore pack. Includes Tools!

Trucraft
PolySaken

An alternative crafting system done entirely in the world.

Base Modpack
karlexceed

This combines several other mods that I consider a basic minimum starting point for worlds.